package main.java.interpreter;

/**
 * 解释器模式
 */
public class Demo {
    public static void main(String[] args) {
        Context context = new Context();

        Variable a = new Variable("a");
        Variable b = new Variable("b");
        Variable c = new Variable("c");
        Variable d = new Variable("d");

        context.assign(a, 1);
        context.assign(b, 2);
        context.assign(c, 3);
        context.assign(d, 4);

        //获取抽象语法树  a-((b-c)+d)

        AbstractExpression expression = new Minus(a, new Plus(new Minus(b, c), d));
        int num = expression.interpret(context);

        System.out.println(expression + "=" + num);
    }
}
